1. Field of the Invention
The present invention relates to a method for making a silicon balloon catheter, and more particularly to a method for making a silicon balloon catheter in which a balloon is formed on a lumen tube having a fluid drainage lumen and an inflation lumen so that it is inflated when a liquid is injected into the balloon though the inflation lumen.
2. Description of the Related Art
In general, a catheter made of silicon is a thin and long tube adapted to be inserted into the human body in order to draw blood or to inject medicine. Also, such a catheter may be used to drain urine. In this case, the catheter is inserted into the bladder through the urethra so as to drain urine collected in the bladder.
FIG. 1 is a sectional view illustrating a conventional balloon catheter. FIG. 2 is a flow chart illustrating a conventional method for manufacturing the balloon catheter.
As shown in FIG. 1, the conventional balloon catheter includes a lumen tube 13 formed with a partition 19 therein to define a primary lumen 12 and an inflation lumen 14, and a balloon layer 16 partially bonded to an outer surface of the lumen tube 13 to provide a balloon. The primary lumen 12 serves to drain urine induced from the bladder through a urine drainage hole 17, whereas the inflation lumen 14 serves to inflate the balloon provided by the balloon layer 16. An inflation hole 15 is also formed at the lumen tube 13 in order to communicate the inflation lumen 14 with the interior of the balloon.
In order to manufacture the balloon catheter having the above mentioned configuration, an extrusion process is carried out to extrude an intermediate tube having the primary lumen 12 and inflation lumen 14 (Step S1), as shown in FIG. 2. Thereafter, the extruded intermediate tube is vulcanized (Step S2), and then cut into tube pieces having a desired length, that is, lumen tubes 13 (Step S3).
Subsequently, the inflation hole 15 and urine drainage hole 17 are perforated through each lumen tube 13 (Step S4). A tip 11 is then formed at one end of each lumen tube 13 (Step S5). Thereafter, a balloon manufactured in a separate molding process (Step S6) is bonded, as the balloon layer 16, to the outer surface of each lumen tube 13 by an adhesive (Step S7). Each lumen tube 13 is then subjected to an overcoating process (Step S8) to complete the balloon catheter having the configuration of FIG. 1.
In the above mentioned conventional balloon catheter, however, there is a problem in that it may cause a patient great pain during a surgical operation because its balloon-bonded portion has a diameter relatively larger than that of other portions, Furthermore, the bonded portions of the balloon maybe separated.
Another conventional catheter manufacturing method is disclosed in U.S. Pat. No. 5,137,671.
This method will be described hereinafter with reference to FIGS. 3a to 3g. First, a double lumen tube 100 is prepared, as shown in FIG. 3a The double lumen tube 100 is formed with a first lumen 120 (a larger fluid conduit lumen) and a second lumen 140 (a smaller capillary lumen).
A capillary lumen access opening 160 is punched through at an intermediate portion of the prepared lumen tube 100, that is, a balloon inflating portion, so that it communicates with the second lumen 140, as shown in FIG. 3b. The second lumen 140 is then filled with a polymeric fill material 180 such as silicon rubber between one end thereof (that is, the left end in FIG. 3b)and a point just before the capillary lumen access opening 160. A tip 200 is attached to one end of the lumen tube 100 corresponding to the one end of the second lumen 140, so that both of the fast and second lumens 120 and 140 are closed at one end thereof.
Subsequently, a portion of the lumen tube 100 extending from one end of the lumen tube 100 to the balloon inflating portion, that is, up to the line Axe2x80x94A in FIG. 3c, is dipped into a bond preventing agent solution (a liquid soap or petrolatum), and then dried, so that it is coated with a solidified bond preventing agent layer 300. The bond preventing agent layer 300 fills the capillary lumen access opening 160 and a portion of the second lumen 140. Thus, the bond preventing agent layer 300 has a cross section as shown in FIG. 3c. That is, the portion of the second lumen 140 between the line Axe2x80x94A and the capillary lumen access opening 160 is filled with the bond preventing agent layer 300, whereas the outer surface portion of the lumen tube 100 between the line Axe2x80x94A and the end of the lumen tube 100 adjacent to the tip 200 is coated with the bond preventing agent layer 300, along with the tip 200.
Thereafter, a portion of the lumen tube 100 extending up to the line Bxe2x80x94B in FIG. 3c, that is, just before the balloon inflating portion, is treated using a surface active agent, and then dipped into hot, water or other hot aqueous solution several times, so as to remove the bond preventing agent layer 300 therefrom. Thus, the bond preventing agent layer 300 remains only at the balloon inflating portion of the lumen tube 100, as shown in FIG. 3d. An overcoat layer 400 is then coated over the entire outer surface of the lumen tube 100, as shown in FIG. 3e. The overcoat layer 400 may have a multi-layer structure including laminated layers 410 and 420.
The remaining bond preventing agent layer 300 filling and covering the balloon inflating portion is completely removed through the second lumen 140 of the lumen tube 100, thereby forming a balloon cavity 440, as shown in FIG. 3f. Thus, a balloon catheter is obtained. Referring to FIG. 3g, it can be seen that the conventional lumen tube 20 has a cross-sectional shape where its thickness ta and thickness Ta are relatively large. Typically, the conventional lumen tube 13 has a minimum thickness between the outer surface thereof and the surface of the inflation lumen 14, that is, ta, corresponding to 0.5 mm, while having a minimum thickness between the outer surface thereof and the surface of the fluid drainage lumen 12, that is, Ta, corresponding to 0.9 mm.
Accordingly, workability in a subsequent operation for perforating inflation apertures while allowing the fluid drainage lumen to have a size as large as possible is significantly reduced.
This balloon catheter manufacturing method has a problem in that it causes environmental pollution due to waste water produced during the procedure of dipping the lumen tube 100 into water several times in order to remove the bond preventing agent from the portion of the lumen tube 100 (between the line Bxe2x80x94B and the tip-side end) other than the balloon inflating portion.
Additionally, where the bond preventing agent is incompletely removed, the residue thereof is moved to the peripheral edge of the balloon cavity formed at the balloon inflating portion when the balloon cavity is inflated, thereby causing the overcoat layer to be stripped around the balloon inflating portion. As a result, the overcoat layer may be inflated around the balloon inflating portion.
Also, the above mentioned conventional balloon catheter manufacturing method still has the problem caused by the diameter of the balloon inflating portion being larger than that of other portions
As another conventional example, there is a silicon rubber catheter disclosed in Japanese Patent No. 3015310 registered on Jun. 21, 1995.
In this catheter, a balloon is formed on the outer surface of a catheter body such that it is integral with the catheter body. The catheter body is formed using silicon rubber in accordance with a primary extrusion process so that it is defined with a fluid conduit lumen and a capillary lumen therein, and formed with a channel at the outer surface thereof The catheter body is subjected to a vulcanization process, and then coated with a bond preventing agent at a balloon forming portion thereof Thereafter, a balloon layer is laminated using silicon rubber over the outer surface of the catheter body in accordance with a secondary extrusion process, and then vulcanized. A tip is then formed at the catheter body. In this structure, the outer surface of the balloon layer is flush with the outer surface of the catheter body at the catheter body portion other than the balloon forming portion, so that there is no step formed at the outer surface of the catheter body. Accordingly, there is no resistance caused by steps.
However, it is difficult to practically manufacture such a catheter, in which the balloon is integral with the catheter body.
This is because the silicon rubber layer coated in the secondary extrusion process may penetrate into the channel. Where the silicon rubber layer is coated without any penetration thereof into the channel, it is difficult to obtain a sufficient bonding force to the catheter body. In this case, the silicon rubber layer may be stripped even at a region other than the balloon forming portion.
Accordingly, the present invention is directed to a silicon rubber balloon catheter that solves the above problems.
An object of the present invention is to not require a step at a balloon portion thereof, thereby being capable of alleviating pain caused to a patient during a surgical operation while preventing a balloon layer from being separated from a region other than the balloon portion.
It is another object of the present invention to achieve an improvement in productivity and a reduction in manufacturing costs.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realize and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for making a silicon rubber balloon catheter, the method comprising the steps of extruding an elongated lumen tube provided with a drainage lumen and an inflation lumen therein, wherein the elongated lumen tube has a diameter less than the silicon rubber balloon catheter; vulcanizing the elongated lumen tube; cutting the vulcanized elongated lumen tube to form one or more unit length lumen tubes; fitting a support rod in the drainage lumen of the unit length lumen tube; forming two apertures through the unit length lumen tube at the a balloon forming region, wherein the two apertures each have a diameter of approximately 0.5 mm; coating an outer surface of the unit length lumen tube uniformly at the balloon forming region with a bond preventing agent while turning the unit length lumen tube along its circumference, wherein the coating of the bond preventing agent has straight edges; removing the support rod from the unit length lumen tube; connecting the coated unit length lumen tube to another coated unit length lumen tube with a connector to form a series of unit length lumen tubes; extruding a balloon tube having uniform thickness over the series of unit length lumen tubes such that the series of unit length lumen tubes is within the balloon tube; ensuring that the bond preventing agent is not discolored or has not deteriorated; vulcanizing the balloon tube; cutting the balloon tube to form one or more unit length balloon tubes, wherein the unit length balloon tube is approximately equivalent in length to the unit length lumen tube; removing the connector from the unit length lumen tube; forming a tip at one end of the unit length balloon tube; and forming a urine drainage hole through the unit length balloon tube and through the drainage lumen within the unit length lumen tube.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide a further explanation of the invention as claimed.